1. Field of the Invention
This invention relates to the treatment of materials and more particularly to a multi-purpose heavy duty centrifugal mill for comminution of various frangible materials such as mined ores, refuse, waste materials and the like.
2. Description of the Prior Art
Many specialized machines have been developed over the years for the comminution of frangible materials such as ball mills for crushing ores and the like. Almost without exception, each machine has been designed to process a particular type of material.
For example, the ever increasing waste disposal problems and interest in the recycling of various materials has in recent years, spurred the design and development of many systems and devices for processing waste and other materials either for more efficient disposal or for recycling purposes. Many elaborate systems and devices have emerged such as the relatively small and simple magnetic separators, air classifiers and the like, all the way to the extremely large processing plants for specialized waste treatment purposes such as automobile crushing and material separating facilities.
In many installations, devices such as the above mentioned air classifiers, magnetic separators, large crushers, and the like are employed in an assembly line like fashion with each device designed to perform a particular function. This technique invariably results in very large and expensive facilities, with the end result being that many locations having relatively low volumes of materials and/or specialized needs simply cannot afford or otherwise justify such installations.
With this in mind, several relatively small and inexpensive machines have been developed for special waste and refuse processing purposes. For example, U.S. Pat. No. 3,987,970 discloses a centrifugal mill for treating solid refuse such as garbage and rubbish of the type normally collected from domestic and relatively small commercial sources. This mill can process such refuse in the dry state with the end product being finely shredded materials suitable for separation and recycling purposes or for increasing the amount of materials which a landfill operation can receive. Further, this mill may treat the solid refuse in conjunction with a fluid carrier medium such as water, aqueous sewage and the like with the end product being a finely shredded pumpable slurry which has been thoroughly aerated to satisfy the biochemical oxygen demand.
Another special purpose centrifugal mill is fully disclosed in U.S. Pat. No. 4,151,794 with this mill being specifically designed to process organic materials such as garbage, animal waste, grass clippings, weeds, cotton stocks, wastes from animal slaughter houses and the like. Depending on the material being process, this mill may be run dry to produce a dry finely shredded end product, may have large quantities of air force fed thereinto for aeration purposes to produce a dry finely shredded odor free product, or may be run simultaneously with air and a liquid carrier medium to produce an odor free pumpable slurry.
The two particular prior art centrifugal mills discussed above are both excellent machines for their intended purposes. However, the first described mill is not particularly well suited for handling the materials that the second described mill is specifically designed to handle and vice versa. This situation is typical in that to the best of my knowledge, no single relatively low cost machine has been devised to process the increasing amounts and great varieties of waste materials and other frangible materials that must be handled.
In view of the above, a need exists for a new and useful multi-purpose heavy duty centrifugal mill which overcomes some of the shortcomings of the prior art.